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Zhangbu Xu (for the STAR Collaboration) Brookhaven National Laboratory

High-p T J/ y at STAR. Zhangbu Xu (for the STAR Collaboration) Brookhaven National Laboratory. Outline: Introduction J/ y yields and suppression J/ y -h correlation Outlook (+MTD). Quarkonia in sQGP. Color screening effect 1) Recombination 2) Gluon energy loss 3)

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Zhangbu Xu (for the STAR Collaboration) Brookhaven National Laboratory

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  1. High-pTJ/y atSTAR Zhangbu Xu (for the STAR Collaboration) Brookhaven National Laboratory • Outline: • Introduction • J/y yields and suppression • J/y-h correlation • Outlook (+MTD)

  2. Quarkonia in sQGP • Color screening effect 1) • Recombination 2) • Gluon energy loss 3) • Heavy quark energy loss 3) • Decay feed-down • (comover, cold matter effect) at (hadronic phase, initial stage) How do the quarkonium behave in the presence of sQGP? 1) T. Matsui and H. Satz, Phys. Lett. B178, 416 (1986) 2) R. L. Thews and M. L. Mangano, Phys. Rev. C73, 014904 (2006) 3) M. B. Johnson et al., Phys. Rev. Lett. 86, 4483 (2001) and R. Baier et al., Ann. Rev. Nucl. Part. Sci. 50, 37 (2000)

  3. H. Satz, Nucl. Phys. A (783):249-260(2007) J/y High pT J/y in heavy ion collisions Hot wind dissociation J/y suppression at low pT could be from suppressed excited states (y’, cc) F. Karsch, D. Kharzeev and H. Satz, PLB 637, 75 (2006) High pT direct J/y suppression  related to hot wind dissociation? H. Liu, K. Rajagopal and U.A. Wiedemann PRL 98, 182301(2007) and hep-ph/0607062 2-component approach Predicted decrease RAA X. Zhao and R. Rapp, hep-ph/07122407 Color singlet model predicted an increase RAA(formed outside of medium) K. Farsch and R. Petronzio, PLB 193(1987), 105 J.P. Blaizot and J.Y. Ollitrault, PLB 199(1987),499 T. Gunji, QM08

  4. The STAR Detector Large acceptance: 2 coverage at mid-rapidity Magnet Coils Central Trigger Barrel (CTB) ZCal Time Projection Chamber (TPC) Year 2000 Barrel EM Cal (BEMC) Silicon Vertex Tracker (SVT)Silicon Strip Detector (SSD) FTPCEndcap EM CalFPD TOFp, TOFr PMD Year 2001+ Future upgrade: Time of Flight, DAQ1000, Heavy Flavor Tracker, Muon Telescope Detector

  5. Low pT J/y in p+p at 200 GeV MC describes position and width J/y trigger 0 < pT < 5.5 GeV/c p+p 200 GeV STAR has J/y capabilities at low pT Mass and width consistent with MC simulation, low mass tail from electron bremsstrahlung Integrated p+p luminosity at 200 GeV: 0.4 (pb)-1

  6. EMC+TPC electrons: |h|<1, pT>4.0 GeV/c TPC only electrons: |h|<1, pT>1.2 GeV/c High pT J/y in p+p at 200 GeV EMC trigger J/y pT p+p 2005 EMC+TPC electrons: |h|<1, pT>2.5 GeV/c TPC only electrons: |h|<1, pT>1.2 GeV/c (S+B)/B: 24/2 3 pb-1 No background at pT>5GeV/c J/y pT p+p 2006 (S+B)/B: 54/14 11 pb-1 Reach higher pT (~14GeV/c)

  7. J/y spectra in p+p at 200 GeV • Significantly extend pT range of previous measurements in p+p at RHIC to 14 GeV/c • Agreement of charm measurements between STAR and PHENIX • Consistent with Color Evaporation calculations (R. Vogt, Private communication)

  8. J/ in Cu+Cu • Signal with good S/B ratio • pT range overlaps with p+p data • Luminosity: 0.9 nb-1

  9. Nuclear modification factor RAA • Double the pT range to 10GeV/c • Consistent with no suppression at high pT: RAA(pT>5 GeV/c) = 0.9±0.2 2s above low-pT data • Indicates RAA increase from low pT to high pT • Doesn’t agree with AdS/CFT prediction • Formed out of medium? • Affect by heavy quark/gluon energy loss • Decay from other particles? 2-component Approach predicted slightly increase RAA after more consideration X. Zhao, WWND2008

  10. SPS: In+In, , consistent with no suppression at pT > 1.8 GeV RAA Comparison to NA60 R. Arnaldi (NA60) QM08 RHIC: Cu+Cu, consistent with no suppression at pT > 5 GeV Cronin pApp Thermal fit Important to understand production mechanism 

  11. NRQCD Quarkonium production mechanism • Color singlet model (CSM) 1) pQCD • Color octet model (COM) 2)  NRQCD • Color evaporation model (CEM) 3) • … • Gluon fusion • Heavy quark fragmentation 4) • Gluon fragmentation 5) • Decay feed-down • … What’s the production mechanism at RHIC energy? 1) R. Baier et al., PLB 102, 364 (1981) 2) M. Kramer, Progress in Particle and Nuclear Physics 47, 141 (2001) 3) H. Fritzsch, PLB 67, 217 (1977) 4) Cong-Feng Qiao, hep-ph/0202227 5) K. Hagiwara et al., hep-ph/0705.0803

  12. ds/dpT [nb/(GeV/c)] Color singlet LHC 14 TeV Tevatron 1.96 TeV LO NLO pT (GeV/c) CSM with kt-factorization PHENIX, PRL 92, 05180 (2004) CSM can also describe the data with some improvement like the kt-factorization approach S.P. Baranov and A. Szczurek arXiv:0710.1792 PRL98, 252002(2007)

  13. xT scaling n is related to the number of point-like constituents taking an active role in the interaction n=8: diquark scattering n=4: QED-like scattering xT scaling: • p and proton: n=6.5±0.8 PLB 637, 161(2006) • J/y: n=5.6±0.2 • J/y production: closer to 22 scattering

  14. (B J/y)/(inclusive J/y) • Generated B spectrum is from pQCD • M. Cacciari, P. Nason and R. Vogt • PRL 95(2005),122001 • 2) Decay BJ/y, kinematics and branch ratio are from CLEO measurements • CLEO collaboration • PRL 89(2002),282001 • BJ/y contributes significantly to the inclusive J/y yields at high pT (>5 GeV/c) • Assuming B production from pQCD (no experimental B spectra at RHIC yet) • Can be used to constrain B production

  15. (e+e-J/y +cc)/(e+e-  J/y + X) = 0.59+0.15-0.13 ±0.12 More J/y production puzzles e+e-, 10.6 GeV B.L. Loffe and D.E. Kharzeev PRD 69, 014016 (2004) Belle, PRL 89, 142001(2002) 0.82 ±0.15 ± 0.14 from new analysis. T. Uglov, EPS 2003 While CEM predict 0.049 D. Kang, et al., PRD 71, 094019 and hep-ph/0412381 NRQCD predict ~0.1 K. Liu and Z. He, PRD 68, 031501 (2003) What happens?: In p+p collisions; At higher energy (200 GeV)

  16. (S+B)/B: 54/14 J/y-hadron correlation Near side correlation Heavy quark fragmentation Good S/B ratio makes this measurement possible RBRC Workshop, BNL, April 23-25, 2008

  17. 1) no near side correlation 2) strong near side correlation PLB 200, 380(1988) and PLB 256,112(1991) Disentangle contributions via Correlations • J/y-hadron correlation can also shed light on different source contribution to J/y production • May be used to distinct CSM and COM

  18. J/y-hadron correlation in p+p • No significant near side J/y-hadron azimuthal angle correlation • Constrain B meson’s contribution to J/y yield • Hints of CSM? h-h correlation PRL 95,152301(2005)

  19. Yields in near/away side • Associated hadron spectra with leading J/y: • Away side: Consistent with leading charged • hadron correlation measurement (h-h)away-side from gluon or light quark fragmentation • Near side: Consistent with no associated hadron production BJ/y not a dominant contributor to inclusive J/y • constrain J/y production mechanism

  20. Constrain Bottom yields • pQCD predicts significant BJ/ • Correlations shows low B contribution • can used to further constrain B yields • PYTHIA productions all show strong near-side correlation  higher order production mechanism?

  21. dE/dx after TOF cut pT (e)>1.5 GeV/c Future dramatic improvement of J / at low pT EMC+TOF (large acceptance): • J / production • Different states predicted to melt at different T in color medium • Charmonia(J/), bottonia () Quarkonium dissociation temperatures – Digal, Karsch, Satz PHENIX Acceptance: |h|<0.35, f=2*p/2 STAR TOF-Upgrade Acceptance: |h|<0.9, f=2*p J/y yields from 109 minbias Au+Au events: 43.8x10-9/0.040x109*292*0.5*1.8*0.5= 144,0000.3% v2 error sJ/y spp N Nbine y RAA

  22. High luminosity for Υ & high-pT J/ RHIC II + DAQ1000: Time-Of-Flight: Enhance statistics Electron identification

  23. +- Longer term: Quarkonia in STAR Heavy Flavor Tracker: ge+e-rejection Topologically reconstruct J/y from B decay Rejection power: ~16 Muon Telescope Detector: Muon identification simulation

  24. +- A novel and compact muon telescope detector for QCDLab • A large area of muon telescope detector • (MTD) at mid-rapidity, allows for the • detection of • di-muon pairs from QGP thermal • radiation, quarkonia, light vector mesons, • possible correlations of quarks and gluons • as resonances in QGP, and Drell-Yan • production • single muons from their semi- • leptonic decays of heavy flavor • hadrons • advantages over electrons: no  • conversion, much less Dalitz decay • contribution, less affected by • radiative losses in the detector • materials BNL LDRD 07—007 project

  25. Concept of Design Detection efficiency muon pion pT (GeV) • A pseudo detector with scintillator covering the whole iron bars and left the gaps in-between uncovered. • muon efficiency: 35-45%, pion efficiency: 0.5-1% • muon-to-pion enhancement factor: 50-100 • muon-to-hadron enhancement factor: 100-1000 including track matching, tof and dE/dx • dimuon trigger enhancement factor from online trigger: 10-50 This together with DAQ1000 will greatly enhance our capability of J/ and other dilepton program in RHIC II and future QCD Lab

  26. Cosmic Ray Results: Long-Strip Multi-gap Resistive Plate Chamber Technology Long MRPC Technology with double-end readout HV: 6.3 KV gas mixture: 95% Freon + 5% isobutane time resolution: ~60 ps spatial resolution: ~1cm efficiency: >95% 950 mm 25 mm 256 mm Y. Sun et al., nucl-ex/0805.2459

  27. USTC Tsinghua module as trigger Scintillator as trigger Fermi Lab Beam Test Results (T963 May 2-15 2007) Y. Sun et al., nucl-ex/0805.2459 HV: 6.3 KV gas mixture: 95% Freon + 5% isobutane time resolution: ~60-70 ps spatial resolution: ~0.6-1cm efficiency: >95% consistent with cosmic test results

  28. STAR-MTD in Year 2007 • iron bars as hadron absorber; two scintillator trays as our trigger • 403 cm away from TPC center, ||<0.25 • gas: 95% Freon and 5% iso-butane; HV: 6.3 KV • MTD Triggered events: 380 K Au+Au events were taken • 1.7 M d+Au and 700 K p+p events taken in run 8

  29. STAR Preliminary STAR Preliminary pT>2 GeV/c Performance at STAR • MTD hits: matched with real high pT tracks • z distribution has two components: narrow (muon) and broad (hadron) ones • spatial resolution (narrow Gaussian) is ~10 cm at pT>2 GeV; hadron rejection: 200-300 • time resolution: 300 ps  Improve our electronics with full scale detector

  30. Compared to Simulation pT (GeV/c) z (cm) muons muons pions from data: pT>2 GeV/c, (z) of muon: ~10 cm from simulation: pT=2.5 GeV/c, (z) of muon: ~9 cm Data and simulation show consistent results

  31. STAR Preliminary pT>2 GeV/c pT>2 GeV/c n>0 n<-1 n>0 Are they prompt muons?

  32. A complete MTD at STAR MTD EMC barrel MRPC ToF barrel Ready for run 10 EMC End Cap RPSD FMS • To install another tray with TOF electronics in run9 • Collaborators for a proposal of full scale detector: 56.6% in azimuth, |eta|<0.88; current tray design: 360 modules, 2160 read-out strips, 4320 channels. (TOF: 23 K readout channels). FPD TPC PMD Complete Ongoing DAQ1000 Ready for run 9 HFT FGT R&D RHIC Science and Technology Review, July 7-9, 2008

  33. Summary (J/y) • J/y spectra in 200 GeV p+p collisions at STAR • Extend the pT range up to ~14 GeV/c • Spectra can be described by CEM and CSM. • High pT J/y follows xT scaling with n=5.6 • Spectra at high pT can be used to constrain B production • J/y-hadron azimuthal correlation in p+p • no significant near side correlationExpect strong near-side correlation from BJ/y+XCan be used to constrain J/y production mechanism • Away-side spectra consistent with h-h correlationindicates gluon or light quark fragmentation • J/y RAA from 200 GeV Cu+Cu collisions at STAR • Extend RAA from pT = 5 GeV/c to 10 GeV/c • Indication of RAA increasing at high pT

  34. Future J/y results from Run 7 Au+Au, data is still under production Upsilon RAA Run 8 (d+Au) just finished, Cold Nuclear Modification Run9—10, Au+Au and p+p runs with TOF and DAQ1000 Longer term: HFT, MTD

  35. Backup slides

  36. Datasets Triggered data High-pT J/y p+p data sample: • 1. J/ψ triggered events in year 2006 • Integrated luminosity: 377 (nb)-1 • 2. Υ triggered events in year 2006 • Integrated luminosity: 9(pb)-1 Au+Au data sample: • 1. Υ triggered events in year 2007 Integrated luminosity: 300(μb)-1 pp-equivalent: 12(pb)-1 p+p data sample: • 1. EMC triggered events in year 2005 ET>3.5 GeV Integrated luminosity: 3 (pb)-1 • 2. EMC triggered events in year 2006 ET>5.4 GeV Integrated luminosity: 11 (pb)-1 Cu+Cu data sample: • 1. EMC triggered events in year 2005 ET>3.75 GeV Integrated luminosity: 0.9 (nb)-1 pp-equivalent: 3 (pb)-1

  37. Muon Identification: dE/dx Effect STAR Preliminary STAR Preliminary STAR Preliminary STAR Preliminary n<-1 n>0 |z|<20 • the narrow Gaussian distribution: dominated by muons Lijuan Ruan (UC Davis Collboration Meeting)

  38. How do I know dE/dx is right? dE/dx: by selecting pions from KS daughter nsigmapion for pion: -1.16 (mean), 1.14 (sigma) Lijuan Ruan (UC Davis Collboration Meeting)

  39. STAR Preliminary STAR Preliminary n>0 STAR Preliminary STAR Preliminary STAR Preliminary Muon Identification: Cut on High Velocity 1/trackhits- 1/rawhits >0 • the narrow Gaussian distribution: dominated by muons Lijuan Ruan (UC Davis Collboration Meeting)

  40. Muons from Pion Decay? Primary tracks Other sector: 4.65e05 pT> 2 GeV/c tracks, 2236 KS reconstructed. MTD matched tracks: 2619 tracks, 3.35.8 KS obsverd. If all muons are from pion decay, 13 KS expected. Consistent with no secondary muon contribution to narrow Gaussian from pion decay. Lijuan Ruan (UC Davis Collboration Meeting)

  41. STAR Preliminary pT>2 GeV/c Muons from Kaon Decay? Left plot:no dE/dx cut Right plot:-5<n<-2.6, Pion(-1.2) Muon(-0.6) Kaon(-2.6), then Muon: 4.8%, Kaon: 48%. I observed 99-1624*4.8%=22 muons. Muons from kaon decay: 22/48%/1624=2.8%. Secondary muons contribution to narrow Gaussian is small from kaon decay. Lijuan Ruan (UC Davis Collboration Meeting)

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